Thrdading-tap



PARKER..

meih mod.

1 of h to be enmved and L w 3 12mg; be varied aC- be puin "mvings to rmed,

The @bow e in the, *1MM 1 Fig. is un fm ing my mpmw Refefrngg n 1.x metals 'mp 1U? shown as' .shown Forum N,

,3.0m mn' 'il lu both man si' the helix indicated b dotted lines, a space 17 (the removed toot i lying in these dotted lines) in the land 14 shown in edge View at the ltop of this ligure is followed, tracin along the helix, by a tooth 15 in the lan 14 in front view which in turn is followed by a space 17 in the land 111, showninedge that one-land 14 is directly opposite and therefore invisible behind the one shown in front view in this figure and that this cut` ting element has the elements 15, 16 and 17 appropriately positioned in the path of the helix not visible.

The particular character of clearance is varied in the manufacture of taps with a .view to 4securing more effective operation on different kinds of material, and it is my intention in embodying my inventions onvarious taps to leave undisturbed the character of relief of some of the teeth remaining after the removal of others of the teeth, but I find most effective results for general use comes from arranging the teeth as above described and the particular character of relief I prefer to give to the teeth with addi tional clearance above referred to is illus trated in the drawings, particularly in the perspective view, Fig. L1. At their cutting edges these teeth have full height and width. The sloping side toward the shank is untouched, leaving a surface which is parallel to the corresponding surface of the adjacent tooth. The other side is cut or drawn away uniformly, while preserving its 60 angle to the axis (or other angle if not a standard thread) from the base to the top, leaving a surface which converges toward the other as this surface approaches the heel of the tooth. The result is that greater relief or clearance is given on the lee side of this tooth, which, -at its cutting edge is the full size of the groove to be formedl The top .or ridge of the tooth slopes inwardly, as appears clearly in Figs. 3 and 4, while the angle at which it converges with relation to the helix is illustrated particularly in Fig. 2. In providing this extra 'or additional relief only one surface needbe operated on. The reduction of the height of the tooth at the heel is incidental and due to the intersection of this surface with the opposite sloping surface of the same tooth.

number of holes to be threaded with a given number of taps is limited much more by breakage than by wear on the taps. Experience has demonstrated that removal of certain teeth increases the average number of holes a tap is capable of threading, and I also yfind that with a given number of taps constructed in accordance with my invention a very much greater number of holes may be threaded than with the standard form of ta s.

am aware that it is old to remove certain teeth of a tap, and I am also aware that it is old to var the shape and arrangement of the teeth uni ormly in any given tap from that described as the usual construction, but I believe that Iam the irst to remove certain teeth of a'tap and modify certain of the re maining teeth in the manner as described and set forth in the following claims.

Having thus described my invention, what I claim is:

i 1. In a threading tap having a plurality of lands separated by flutes, teeth spaced unequally but in multiples of the pitch and unequal clearances. tap having a land comprising a plurality of teeth separated into groups by a vplurality of spaces, certain of said teeth having more relief than others.

3. In a threading tap comprising a tapered cylinder, having a helical thread thereon, and having fluted portions removed and teeth formed from the remaining portions of the helix, spaces formed therein by the removal of certain teeth at regular intervals, and certain of the remainin teeth :in regular sequence along the helix aving more clearance than others.

4. In a threading tap having helical teeth, a space in one landbeing preceded and followed in the helical path in adjacent lands by teeth having clearance greater than normal.

5. In a tap having helical teeth, a tooth in one land being preceded and followed in the helical path in adjacent lands by teeth having clearances greater than normal.

6. In a threading tap, a land having a tooth arrangement comprising a tooth of minor clearance, a tooth of major clearance, and a space.

7. A tap having a plurality of lands, each land having a third of the teeth removed, half of the remaining teeth having greater clearance than the others.

8. A tap having the teeth removed at regular intervals along each land, forming spaces, the teeth on either side of each space being provided with different clearances.

9. A tap having a third of its tooth space on each land provided with teeth of minor clearance, a third with teeth of major clearance, and a third with spaces formed by the removal of teeth.

yw a partv Wthteeth i0. A tap iiai'iiig a portion of its ee'ctive lmeth on each land of :i dearance dierent imm ha; or he'remainder.

l. A mp having half of its eiective teeth' mjoi clem-mice boing formed by uniformly reducing one fade 'of the tooth behind the, cutting edge.

in testimony whei'so'f, heieunto aiiix my signature, in. the presence of two Witnesses.

SOHN MUTH.

Witnesses i i Faim J. Hausa,

L. HOUR: 

